In conventional energy distribution networks, the energy consumption of a site is typically measured at a central supply point, e.g., between a supply line of the energy supplier and the first distribution panel of a given site, for example, a single building or a distinct part of a building such as an apartment or the like. In this way, all electrical energy consumed at that particular site can be measured, irrespective of the electrical distribution system of the given site.
Conventional energy metering devices locally record the total use of electrical energy. Such energy metering systems need to be read at regular intervals by the energy consumer, the energy provider or a service company. More recently, so-called smart metering devices have been introduced in several countries. In a smart metering system, a smart metering device communicates the amount of energy consumed at a particular site back to a utility provider, e.g. the energy provider or a service company. In some instances, the amount of energy consumed is reported on request only, e.g. for preparation of a utility bill. Other smart energy metering systems allow a more regular feedback of energy consumption data, for example every day or every hour. In any case, the energy consumed by such energy metering devices is provided by an electrical supply line, to which it is connected.
Reporting an energy consumption back to the utility provider at regular intervals allows the implementation of new charging policies. For example, energy consumers may be rewarded with lower prices by an energy provider if they avoid excessive energy consumption in times of high demand, and instead shift their energy consumption to periods of low demand, such as the night.
While such systems are useful on a macroscopic level, in many cases, energy metering systems measuring the energy consumption of a relatively large site at a single point are insufficient in order to analyze the energy consumption of a single user in detail. For example, a user may detect that he or she uses an above-average amount of energy at a particular time of the day but may be unable to detect where in the house or apartment this energy is consumed.
To overcome this problem, devices have been developed that allow the measurement of the electrical load of a particular device. Such devices can either be installed fixedly at relevant points of an energy distribution network or may be provided as an intermediate device, plugged in between a wall outlet and a device under scrutiny. While these devices are useful in identifying electrical devices causing a particularly high electrical load, such devices are often difficult to install and operate. Moreover, such devices consume at least some of the electrical energy charged to the customer, making it unattractive to install them permanently.
In this context, it is a challenge of the present invention to describe energy metering systems and associated devices that allow an energy consumer or a utility provider to obtain a more detailed assessment of the electric energy consumption at a particular site. Preferably, the energy metering system should consume as little energy itself as possible and be easy to deploy and operate.